Continuous non-invasive sphygmomanometer

ABSTRACT

According to the invention a sphygmomanometer for continuous plethysmographic measurement of blood pressure includes at least one inflatable pressure pad which is attachable to a body part containing an artery, arterial signal sensors for determining arterial blood flow, and a valve-controlled pressure chamber connected to a gas source and to the inflatable pressure pad and including a pressure sensor for measuring the pressure in the pressure chamber or in the pressure pad. The pressure chamber has separate inlet and outlet valves which are controlled dependent on signals of the arterial signal sensors.

BACKGROUND OF THE INVENTION

In medicine there is a need to frequently, and possibly, continuouslytake blood pressure. Novel devices have been created In recent times forthis purpose, The method devised by Panaz contributed an essentialnovelty (Digest of the 10^(th) International Conference on Medical andBiological Engineering 1973 Dresden), wherein light is shone through afinger and the registered flow Is kept constant by a booster control.

This photoplethysmographic method was taken up by several others also(Yamakoshi, Wesseling, TNO). EP 537 383 (TNO) Apr. 21, 1993 (21.04.93)discloses an inflatable finger cuff used for non-invasive continuousmonitoring of blood pressure. The inflatable cylindrical space isconnected pneumatically to a fluid source. An infrared light source anda detector are positioned on both sides of the finger inside the fixedcylinder. A valve is provided for filling the cylinder with gas.Electrical cables for the infrared light source and the detector arethreaded through. U.S. Pat. No. 4,510,940 A (WESSELING) Apr. 16, 1985(16.04.85) and U.S. Pat. No. 4,539,997 A (WESSELING) Sep. 10, 1985(10.09.85) disclose a device for continuous non-invasive measuring ofblood pressure. A fluid-filled cuff, a light source, a light detectorand a differential pressure booster are provided. U.S. Pat. No.4,406,289 A (WESSELING) Sep. 27, 1983 (27.09.83) also discloses such adevice according to the prior art.

The cited documents all show prior art only, especially so when it isconsidered that features essential to the invention are missing in themain claim.

A major problem of these methods is on the one hand in the cuffs beingused which have to be placed very precisely, are very interference-proneand not very durable, and on the other hand is with the proportionalvalves used which are very expensive to manufacture (U.S. Pat. No.4,406,289) and also in the calibrating of the device which can veryprecisely indicate the relative fluctuations in blood pressure, whereinabsolute measuring however deviates considerably from the actualintra-arterial values. Usually, with the proportional valves used todate either a) a toggle flapper is used, which can be moved alternatelyin one or the other direction by an electromagnet, or b) anelectromagnetic shaker is used. With both these proportional valvesthere is a constant gas flow through the pressure chamber, as there is apart of the valve always open. Either the outlet opening is releasedinto the open, or the inlet opening is released by the gas supply. Thereis no position of the valves, in which both inlet and outlet opening aresimultaneously closed.

This results in very high gas consumption, of little relevance in fixedapparatus, but clearly significant in the case of portable units. Afurther drawback is the use of pressure generation systems (usuallypumps and compressors) which must generate a pressure flow withoutripple, since any such ripple would influence the measuring signal.Pumps or compressors generating a constant and even air flow aregenerally more expensive and consume more power than pressure generationsystems delivering a pressure which may not be under a specificthreshold. The weight or the power consumption of the unit is clearlyincreased.

Yet another disadvantage of the methods utilised is that such methodsused to date are employed exclusively on fingers, and the fingerarteries belong to the small arteries which are regulated in the flowfrom the body for example by the temperature of the fingers, so that thepressure in these arteries no longer corresponds to the pressure in thelarge arteries, in which doctors are primarily interested. For thisreason the devices used hitherto (for example the Finapres marketed byOhmeda) very clearly give the relative fluctuations in blood pressurebut not in absolute values of the pressure, so that the Finapres unitwas also removed from the market.

Another existing sphygmomanometer essentially uses planartonometry. Anarray of very small pressure receivers, which are embedded in silicon,is applied to the artery by means of compressed air bellows, whereby acomputer searches out the pressure sensor outputting the clearestsignal. The pressure in the bellows is no longer altered after a clearsignal has been found, while the pressure curve is calibrated by one-offor multiple measuring of the oscillometric blood pressure which can bemeasured intermittently on the same upper arm. When a hard object isapplied, namely the array onto the artery, the former deforms in anuncontrollable manner, so that the pressure values output by this unitdeviate very strongly from the intra-arterial values. (Zorn et al, BloodPressure Monitoring 2: 185, 1997). Precise analysis of the pressurecurves can additionally be employed by means of an expanded Windkesselmodel in known fashion to evaluate compliance of the large and smallvessels, as demonstrated by Waft and Burrus. Furthermore, the pressurein the central aorta can also be calculated by computer, for examplewith frequency analyses, or a so-called augmentation index can also becalculated which clearly reflects the actual mechanical strain on theheart and vascular system. To date the so-called aplanation tonometry,wherein a hard pressure sensor was applied by hand or per micrometerscrew to the artery, has been used to relieve arterial wall. Thedisadvantage of this so far has been that the pressure lying on theartery because of the pressure sensor was not known, and that it wasexceedingly troublesome to accurately find the artery by hand.

The object of the present invention is to prevent these knowndifficulties by developing a new sphygmomanometer.

SUMMARY OF THE INVENTION

According to the invention a sphygmomanometer for continuousplethysmographic measurement of blood pressure includes at least oneinflatable pressure pad which is attachable to a body part containing anartery, arterial signal sensors for determining arterial blood flow, anda valve-controlled pressure chamber connected to a gas source and to theinflatable pressure pad and including a pressure sensor for measuringthe pressure in the pressure chamber or in the pressure pad. Thepressure chamber has separate inlet and outlet valves which arecontrolled dependent on signals of the arterial signal sensors.

The sphygmomanometer according to the invention is described in greaterdetail with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the new blood pressure measuring system according to theinvention;

FIG. 2 shows the new finger cuff in greater detail;

FIG. 3 illustrates an embodiment of the blood pressure measuring system,wherein pressure sensors are used as arterial signal sensors

FIG. 4 illustrates an embodiment of the blood pressure measuring system,wherein several signal sensors are used as arterial signal receivers;and

FIGS. 5, 6 and 7 are detailed illustrations of the arterial signalreceivers,

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1 the gas source is designated by reference numeral 1, whichcould refer to an air pump or also to a gas cartridge. An attenuator padis designated by 2, for example a gas filter, which would equilisehigh-frequency irregularities of the gas supply, for example when amembrane pump is being used as a gas source and at the same time servesas dust filter. The pressure chamber is designated by 3, whereby theconnection to gas source 1 is established by an inlet valve 4. Theoutlet valve is designated by 5. The valves could be conventionalproportional valves, while the use of valves with very short responsetimes is particularly beneficial, as given for example by piezoelectricelements. Response times for these piezoelectric valves of around amillisecond can give rise to pressure changes here which can be in afrequency range of up to 50 Hz. With the use of piezoelectric valves thevalves can be controlled digitally and especially easily by a computer10, so that characteristics can be imparted to the valves by way of thisdigital control, not attainable or only with difficulty so withconventional proportional valves or with forced coupling of outlet andinlet valve (such as for example in U.S. Pat. No. 4,406,289 Wesseling).Each desired pressure cycle can thus be adjusted in pressure chamber 3with an upper limit frequency of ˜50 Hz and gas consumption can also bekept low.

Pressure chamber 3 can be connected via another reversing valve 6 forexample with two or more pressure pads 7 by way of lines 3 a and 3 b ofpressure chamber 3, which serve as artery compression. If only onepressure pad is used reversing valve 6 can be omitted. The relativelyrigid outer wall is designated by 8. Its purpose is to keep thecompliance of pressure pad 7 low. Reference numeral 9 designates amouldable membrane which serves as artery compression. In a special casepressure pads 7 are distinguished as annular in cross-section, becausethey are designed for use on fingers, by which pressure pad 7 isattached. Reference numeral 11 designates a rigid positioning component,by means of which both pressure pads 7 can be connected. The advantagehere is that the position of pressure pads 7 on the fingers isguaranteed in relatively constant alignment. A constant position ofarterial signal sensors 12 applied to the limit of pressure pads 7relative to the artery lying beneath mouldable membrane 9 is guaranteed.With arterial signal sensors 12 it could be a matter of, for example,light sources and light sensors (arterial signal receivers 12 a andarterial signal senders 12 b) which measure the flow of the artery, oralso ultrasound sensors or lasers or even pressure sensors. Therefore,controlled by arterial signal receivers 12, which are likewise attachedto computer 10, the desired pressure can be produced any time inpressure pad 7. Instead of pressure pads 7 illustrated here as annularin shape, any other shape adapted to the body part in use could be usedin this instance. Should the sphygmomanometer be used for example on theskull above the arteria temporalis, flat pressure pads 7 would besuitable.

Moreover, anywhere in the vicinity of the communicating interstice,formed by pressure chamber 3 and pressure pad 7, a pressure sensor 13 isattached which measures the pressure in the pressure chamber andforwards the results to computer 10. The pressure measured in thepressure chamber with appropriate control by means of arterial signalsensors 12 corresponds to the arterial pressure. By way of advantagewith the illustrated pressure sensor 13 it could well be a matter of adifferential pressure sensors. The advantage of this would be thatpressure measuring can be corrected any time to the artery heightdifference, relative to the heart. For this a fluid-filled line wouldhave to be available which reaches the level of the heart (symbolicallyillustrated in FIG. 1 with a heart). By way of advantage fluid-filledline 14 is filled with a fluid which corresponds to the density ofblood. The fluid, with which line 14 is filled, should exhibit a slightoutput coefficient (for example oily fluids). The hose can be attachedby means of a fastening mechanism 14 a (such as a locking band, pressureknob, clamp and the like) to the extremity (for example upper arm orarticle of clothing) at heart level. A free-floating membrane 14 b,which prevents the fluid from escaping, but which allows the fluidcolumn to move, could be attached at the heart end of line 14. Anotherair-permeable but hard-wearing membrane 14 c or a fine-mesh grille 14 c,which prevents free-floating membrane 14 b from being damaged, could beattached via free-floating membrane 14 b.

Another pressure pad 15 can also be added, which comes to rest viaanother artery, preferably a major artery, which can be connected toanother gas source 16 to measure the blood pressure thereconventionally, for example oscillometrically or auscultatorically. Inthe same way and with adequate capacity gas source 1 could be used,effectively necessitating more valves (not illustrated). It is knownthat conventional blood pressure measuring, such as auscultatoric oroscillometric measuring, works intermittently, that is, normally atintervals of minimum half a minute to a minute. The other pressure padis likewise connected to computer 10, so that calculation and display ofthe continuous arterial pressure, as determined in the small artery bypressure pad 7, is automatically corrected to the true value of theblood pressure in the major artery, as is measured by pressure pad 15.

The added advantage of the second pressure measuring via a major arteryby pressure pad 15: for continuous measuring of pressure by pressure pad7 the pressure in pressure pad 7 must constantly track the averagearterial pressure, that is, the operating point must be readjusted. Toreadjust the operating point the continuous blood pressure measuringmust be briefly interrupted by pressure pad 7. Major changes in theaverage arterial pressure can now be discovered by measuring pressure inanother artery by pressure pad 15 discontinuously, and the operatingpoint can be continually adapted automatically and without interruptionto the continuous measuring of pressure by pressure pad 7. In this waycontinuous, unbroken recording of the true intra-arterial pressure curveis possible using the abovedescribed sphygmomanometer. By changingautomatically from one pressure pad 7 to the other pressure pad 7 a viareversing valve 6 measuring of pressure is not interrupted, since thepatient does not experience any discomfort from continuous measuring onthe same spot.

FIG. 2 illustrates an advantageous embodiment of pressure pad 7 whichcomprises a relatively rigid outer wall 8 which on the one hand givespressure pad 7 beneficial minimal compliance, and on the other handallows rigid connection 11 to adjacent pressure pad 7 a which isdesigned similarly. Located inside relatively rigid outer wall 8 ismouldable membrane 9, on which in the illustrated case arterial signalsensors 12 rest. There is thus no interfering membrane between arterialsignal receivers (flow sensors) 12 and arteries 17 which might impairmeasurement of the blood flow. As mentioned, these flow sensors could beLED's combined with light detectors, (for example photodiodes), lasers(or laser diodes) and photodiodes or ultrasound emitters and receivers(arterial signal receivers 12 a and arterial signal receivers 12 b).Using other pressure sensors (see FIG. 3) is also feasible. Recesses 18,into which arterial signal sensors 12 can disappear, are realisedadvantageously in the relatively rigid outer wall for arterial signalsensors 12 when mouldable membrane 9 is close to rigid outer wall 8.This close fit is accordingly meaningful to keep the compliance ofpressure pad 7 to a minimum. In the illustrated example two arterialsignal receivers 12 a and 12 b are attached to one another at an angleof 120° to ensure an optimum signal, arteries 17 lie relative to fingerbone 19 in finger 20, corresponding to an angle of 180° in illustratedpressure pad 7, and the clearest signal is emitted, when arterial signalreceivers 12 a and arterial signal receivers 12 b are positioned at ca.120° to one another, as already mentioned, since at the same time aneven better and more homogeneous pressure can be exerted on the artery.This is therefore the case because then only mouldable membrane 9, andnot arterial signal receivers 12 a and 12 b, which are not mouldable,which comes to rest on artery 17.

In the illustrated example mouldable membrane 9 consists of gas-tightand fluid-tight synthetic material. In order to make measuring morepleasant for the patient, a skin-friendly tissue 21 is additionallyapplied between mouldable membrane 9 and the body, which for examplecould comprise nylon or other synthetic tissues, cotton or similar. Inthe process the skin-friendly tissue releases arterial signal receivers12 a and 12 b, so that the signal is not impaired. Of particular benefitare those materials which can readily be cleaned or disinfected.Electrical shielding 22 is also provided which keeps electricalinterference away from arterial signal receivers 12. In the illustratedexample electrical shielding 22 is applied externally on rigid outerwall 8, but could also be placed inside rigid outer wall 8.

To ensure correct positioning of arterial signal sensors 12 above artery17, if only one pressure pad 7 is present, it can be beneficial to alsomount rigid positioning component 11 on rigid outer wall 8, if only onepressure pad is used. Rigid positioning component 11 is then formed tothe adjacent body structures (in the case of a finger for example theadjoining fingers, back of hand, palm; in the case of the thumb the ballof the thumb, not illustrated) and could thus also take on a ring shapeor form parts of a ring.

As illustrated in FIG. 3, it can be beneficial to mount pressure sensorsas arterial signal sensors 12 in rigid outer wall 8. In this illustratedexample it can be beneficial to divide the communicating system,comprising pressure chamber 3 and pressure pad 7, by additional easilymouldable septums 23 which create separate areas 24 a and 24 b in thepressure chamber. Area 24 a located in the vicinity of the arterialsignal receivers could then be filled with another medium, namely withfluid, to better transmit the signals emitted by the artery to thearterial signal receivers. Reference numeral 25 designates a filling orventilating aperture which can be sealed and which is located inrelatively rigid outer wall 8, by way of which sector 24 a can be filledwith a fluid. The advantage of this embodiment is that in the concreteexample arterial signal sensor 12 can also be a high-resolution pressurereceiver which can absorb the pure, unattenuated signals from artery 17lying on bone 26, without impairing these mechanically. In this way thecontinuous pulse curve can be recorded ongoing in high resolution, whilea precisely known pressure of artery 17 can be applied via flexibleseptums 23. The arterial wall can thus be relieved, and a pure pulsecurve can be recorded continuously.

In the embodiment used here blood pressure can be measured usingpressure sensor 13, which is connected to sector 24 b of pressure pad 7,also oscillometrically in known fashion, and then with knowledge of thesystolic, diastolic and average arterial pressure, any desired pressurein relation to the systolic, diastolic and average arterial pressure inpressure pad 7 and thus also in fluid-filled area 24 a can be created inorder to thus record the pulse curve with precisely defined pressureratios and thus to enable continuous bloodless recording of bloodpressure. It is understood that other arterial signal sensors 12(receiver 12 a and sender 12 b), as for example light-sensitive sensorsand LED's can be installed in the rigid outer wall.

As illustrated in FIG. 4, several arterial signal receivers (12 a-d) maybe present, whereby a multiplex switch 27 and computer 10 carry out thechoice of the optimally placed arterial signal receivers 12 a-d in orderto receive an optimum arterial signal. This is particularly beneficialfor enabling interference-free recording of signals when the artery isin a position altered from individual to individual. It would be ideal,instead of localizing pressure pad 7 above a small artery, for examplethe finger artery, with the necessity of recalibrating the measuring byanother pressure pad 15 which lies above a large artery, to utilise justone pressure pad 7 from now on over a major artery, which allowscontinuous measuring of pressure and at the same time the absolutevalues can be correctly determined. An example of such an artery is thearteria radialis or temporalis, which is on the one hand large enough tobe representative of the major arteries, but on the other hand stillallows recording of arterial signals, such as flow metering byirradiation or reflection on underlying bone 26 (for example, the radiusor skull bones) by waves emitted to arterial signal senders 12 b. Theadditional advantage of the arteria radialis for example is that yetanother artery, namely other artery 17 a in this instance the arteriaulnaris, is available. For measuring only artery 17 has to be compressedby pressure pad 7, and not other artery 17 a and the blood flow to theextremity is consequently not interrupted. In addition, only mouldablemembrane 9 has to be inflatably connected to a sector 28 of rigid outerwall 8 in that area which lies above artery 17 being examined, whileother artery 17 a is not compressed by mouldable membrane 9.

FIG. 5 illustrates a practical realisation of the device, as it isadvantageous if the arterial signal receivers (receiver 12 a and sender12 b) are supported on mouldable membrane 9. In this case the mouldablemembrane, which may comprise latex, for example, is not interrupted,rather arterial signal sensor 12 is cast in a mouldable lens 29,preferably from the same material as mouldable membrane 9, which isattached to membrane 9 (for example stuck or vulcanised). At the sametime electrical wires 30 are guided between mouldable membrane 9 andskin-friendly tissue 21, so that these wires can also be guided tocomputer 10 while shielded mechanically and insulated.

FIG. 6 illustrates another embodiment of the planned device, whereinarterial signal sensors 12 are applied to a strip 31, whereby strip 31represents a part of septum 23 which separates gas-filled area 24 b fromfluid-filled area 24 a. Gas-filled area 24 b is drawn through on theside turned away from the body, so that when the pressure in pressurechamber 3 is raised (and thus in gas-filled area 24 a) the arterialsignal receivers cannot or can only slightly alter their position toartery 17 and in any case cannot be lifted from the body. An optimumsignal is always obtained from arterial signal sensors 12 independentlyof the pressure in pressure chamber 3. So that arterial signal sensors12 in strip 31 cannot tilt, an additional one, preferably two stayers 32are solidly connected to strip 31, and are mounted movably in relativelyrigid outer wall 8, in guide openings 33, for example. And so thatoptimum pressure transmission without loss of pressure from area 24 b toarea 24 a is possible, strip 31 is narrow so that septum 23 can transmitthe pressure from area 24 b to area 24 a from several sides.

As FIG. 7 illustrates stayers 32 are passed by outside gas-filled area24 b of pressure pad 7 so that pressure pad 7 does not have to beinterrupted.

Legend  1 gas source  2 attenuator  3 pressure chamber  4 inlet valve  5outlet valve  6 reversing valve  7 pressure pad  8 rigid outer wall  9mouldable membrane 10 computer 11 rigid positioning component 12arterial signal sensors 12a arterial signal receiver 12b arterial signalsender 13 pressure sensor 14 fluid-filled line 14a fastening device 14beasily mouldable floating membrane 14c hard-wearing, air-permeablemembrane 15 other pressure pad 16 additional gas source 17 artery 17another artery 18 depressions 19 finger bones 20 finger 21 skin-friendlytissue 22 electrical shielding 23 septums 24a 24b separate areas 25ventilating apertures 26 bones 27 multiplex switch 28 outer wall sector29 mouldable lens 30 electrical wires 31 strip 32 stayer 33 guideopenings

What is claimed is:
 1. A sphygmomanometer for continuousplethysmographic measurement of blood pressure, comprising: at least oneinflatable pressure pad which is attachable to a body part containing anartery; arterial signal sensors for determining arterial blood flow; avalve-controlled pressure chamber connected to a gas source and to theinflatable pressure pad, having a pressure sensor for measuring thepressure in the pressure chamber or in the pressure pad; and a computer,with valve control of the pressure chamber dependent on signals of thearterial signal sensors; wherein the pressure chamber is fittedrespectively with a separate inlet and outlet valves.
 2. Asphygmomanometer as claimed in claim 1, wherein an arterial signalreceiver and an arterial signal sender are machined into a mouldablemembrane of said pressure pad and wherein in a rigid outer wall of thepressure pad is available, containing depressions for the arterialsignal sensor.
 3. A sphygmomanometer as claimed in claim 1, wherein thepressure pad is annular in shape.
 4. A sphygmomanometer as claimed inclaim 1, wherein the pressure pad exhibits a rigid outer wall with atleast one rigid positioning component.
 5. A sphygmomanometer as claimedin claim 4, wherein the rigid positioning component presents a ring orparts of a ring.
 6. A sphygmomanometer as claimed in claim 5, wherein anadditional pressure pad is located in an additional ring of thepositioning component, and wherein a reversing valve is arrangedupstream of the pressure chamber with which the pressure pads can beimpacted with pressure alternately.
 7. A sphygmomanometer as claimed inclaim 1, wherein a further pressure pad is provided on another body partwith an artery for conventional, intermittent, oscillatory orauscultatoric measuring of blood pressure, with the operating point forcontinuous measuring of blood pressure being regulatable by said furtherpressure pad.
 8. A sphygmomanometer as claimed in claim 7, wherein thecomputer continuously standardizes the continually measured bloodpressure to the blood pressure measured intermittently said furtherpressure pad.
 9. A sphygmomanometer as claimed in claim 1, whereinseveral arterial signal sensors are provided, from which the computersearches out and controls the arterial signal sensor(s) with the bestsignal characteristic.
 10. A sphygmomanometer as claimed in claim 1,wherein only one sector of a rigid outer wall of the pressure pad,containing the arterial signal sensors, is lined with a mouldablemembrane.
 11. A sphygmomanometer as claimed in claim 1, wherein thearterial signal sensors are applied at an angle of about 120° to oneanother.
 12. A sphygmomanometer as claimed in claim 1, wherein thepressure sensor of the pressure chamber is a differential pressuresensor, whose one part is connected to the interior of the pressurechamber or to the pressure pad and whose other part is connected to afluid-filled line.
 13. A sphygmomanometer as claimed in claim 12,wherein the fluid-filled line is filled with a liquid of low vaportension.
 14. A sphygmomanometer as claimed in claim 13, wherein thefluid-filled line is sealed at its side facing away from thedifferential pressure sensor with a deformable membrane.
 15. Asphygmomanometer as claimed in claim 14, wherein the deformable membraneis surrounded on its outside by a rigid, air-permeable membrane.
 16. Asphygmomanometer as claimed in claim 12, wherein the fluid-filled lineis fitted with a fastening device on its heart end.
 17. Asphygmomanometer as claimed in claim 1, wherein a gas cartridge is usedas gas source.
 18. A sphygmomanometer for continuous plethysmographicmeasurement of blood pressure, comprising: at least one inflatablepressure pad which is attachable to a body part containing an artery;arterial signal sensors for determining arterial blood flow; avalve-controlled pressure chamber connected to a gas source and to theinflatable pressure pad, having a pressure sensor for measuring thepressure in the pressure chamber or in the pressure pad; and a computer,with valve control of the pressure chamber dependent on signals of thearterial signal sensors; wherein at least one arterial signal sensor ismachined into the side of the pressure pad facing away from the body;and wherein the pressure pad is separated by at least one mouldableseptum into separate areas, which areas are filled with different media,for example gas or fluid, with at least one arterial signal sensor beingassigned to one of the separate areas.
 19. A sphygmomanometer as claimedin claim 18, wherein the arterial signal sensors are taken up in theside of the mouldable septum facing away from the body.
 20. Asphygmomanometer as claimed in claim 19, wherein the arterial signalsensors are arranged on a strip.
 21. A sphygmomanometer as claimed inclaim 20, wherein the strip is mounted movably opposite a rigid outerwall of the pressure pad.
 22. A sphygmomanometer as claimed in claim 21,wherein the strip has stayers which are guided movably in guide openingin the rigid outer wall of the pressure pad.
 23. A sphygmomanometer asclaimed in claim 3, wherein the pressure pad is annular in shape.
 24. Asphygmomanometer as claimed in claim 3, wherein a further pressure padis provided on another body part with an artery for conventional,intermittent, oscillatory of auscultatoric measuring of blood pressure,with the operating point for continuous measuring of blood pressurebeing regulatable by said further pressure pad.
 25. A sphygmomanometeras claimed in claim 3, wherein only one sector of a rigid outer wall ofthe pressure pad, containing the arterial signal sensors, is lined witha mouldable membrane.
 26. A sphygmomanometer as claimed in claim 3,wherein a gas cartridge is used as gas source.
 27. A sphygmomanometer asclaimed in claim 3, wherein the arterial signal sensors are mounted in amouldable lens and wherein all electrical connections are guided to thearterial signal sensors outside of the pressure pad and inside askin-compatible tissue.
 28. A sphygmomanometer for continuousplethysmographic measurement of blood pressure, comprising: at least oneinflatable pressure pad which is attachable to a body part containing anartery; arterial signal sensors for determining arterial blood flow; avalve-controlled pressure chamber connected to a gas source and to theinflatable pressure pad, having a pressure sensor for measuring thepressure in the pressure chamber or in the pressure pad; and a computerwith valve control of the pressure chamber dependent on signals of thearterial signal sensors; wherein the pressure chamber comprises aseparate inlet valve and a separate outlet valve; and wherein severalarterial signal sensors are provided, from which the computer searchesout and controls the arterial signal sensor(s) with the best signalcharacteristic.
 29. A sphygmomanometer for continuous plethysmographicmeasurement of blood pressure, comprising: at least one inflatablepressure pad which is attachable to a body part containing an artery;arterial signal sensors for determining arterial blood flow; avalve-controlled pressure chamber connected to a gas source and to theinflatable pressure pad, having a pressure sensor for measuring thepressure in the pressure chamber or in the pressure pad; and a computer,with valve control of the pressure chamber dependent on signals of thearterial signal sensors; wherein the pressure chamber comprises aseparate inlet valve and a separate outlet valve; and wherein only onesector of a rigid outer wall of the pressure pad, containing thearterial signal sensors, is lined with a mouldable membrane.
 30. Asphygmomanometer for continuous plethysmographic measurement of bloodpressure, comprising: at least one inflatable pressure pad which isattachable to a body part containing an artery; arterial signal sensorsfor determining arterial blood flow; a valve-controlled pressure chamberconnected to a gas source and to the inflatable pressure pad, having apressure sensor for measuring the pressure in the pressure chamber or inthe pressure pad; and a computer, with valve control of the pressurechamber dependent on signals of the arterial signal sensors; wherein thepressure chamber comprises a separate inlet valve and a separate outletvalve; and wherein the arterial signal sensors are applied at an angleof about 120° to one another.
 31. A sphygmomanometer for continuousplethysmographic measurement of blood pressure, comprising: at least oneinflatable pressure pad which is attachable to a body part containing anartery; arterial signal sensors for determining arterial blood flow; avalve-controlled pressure chamber connected to a gas source and to theinflatable pressure pad, having a pressure sensor for measuring thepressure in the pressure chamber or in the pressure pad; and a computer,with valve control of the pressure chamber dependent on signals of thearterial signal sensors; wherein the pressure chamber comprises aseparate inlet valve and a separate outlet valve; and wherein thepressure sensor of the pressure chamber is a differential pressuresensor, whose one part is connected to the interior of the pressurechamber or to the pressure pad and whose other part is connected to afluid-filled line.